https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70055
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Note the choice of this in a header file is obviously wrong, if you at some point fix this up, then apps will still call memcpy rather than mempcpy, even when the latter is more efficient (because it doesn't have to save the length value in some location where it survives across the call). Note if you don't use the result of mempcpy, gcc is able to optimize it into memcpy, and tons of other optimizations.
